Other Assets, Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Other assets
Earnest money and refundable deposits	$ 763.4	$ 657.1
Insurance receivables	82.2	81.2	$ 76.9
Other receivables	145.6	143.1
Prepaid assets	53.4	46.0
Margin deposits	33.4	16.2
Contract assets - insurance agency commissions	49.1	47.1
Lease right of use assets	33.4	34.7
Mortgage servicing rights	9.8	17.1
Other	39.5	39.9
Other assets	1,236.2	1,113.7
Accrued expenses and other liabilities
Reserves for legal claims	491.8	473.8	432.5	$ 434.7
Employee compensation and related liabilities	361.8	376.1
Warranty liability	324.0	310.2	$ 251.6	$ 247.3
Mortgage hedging instruments and loan commitments	41.3	16.5
Accrued interest	37.9	35.3
Federal and state income tax liabilities	281.8	42.6
Inventory related accruals	68.5	59.7
Customer deposits	110.5	93.1
Accrued property taxes	32.6	44.1
Lease liabilities	35.5	37.0
Other	153.2	118.6
Accrued expenses and other liabilities	1,938.9	1,607.0
Interest rate lock commitments [Member]
Other assets
Interest rate lock commitments	$ 26.4	$ 31.3